Practical Center Notes

Get an easy reading practice for students taking the KPK board (Mardan board) exams in the 9th-grade Biology Class 9th Notes Chapter 6 Enzymes Book Note of perfect24u. Chapter 6 Enzymes - Short Questions Q.1) Differentiate between the lock and key model and the induced-fit model. Answer: Lock and key  model Induced fit model This model was proposed by a German chemist, Emil Fischer in 1894.This model was given by an American biologist, Daniel Koshland in 1958.According to this model, the active site of the enzyme and the substrate have specific geometric shapes.According to this model, when a substrate molecule fits in the enzyme's active site, the enzyme molecule alters the shape of the active site slightly so that it fits more tightly around the substrate molecule.This model suggests that the active site is a rigid and non-flexible structure.                                                                                                                                            ...

Make an informal reading practice for students exercising the KPK board exams in the Biology Class 9th Notes Chapter 8 Nutrition Mardan board Book Note of perfect24u. Chapter 8 Nutrition Mardan board Q.1) List all the parts(in order)of the human digestive system through which food passes. Answer: Parts of human digestive system through which food passes: 1- Oral cavity 2- Pharynx 3- Oesophagus 4- Stomach 5- Small intestine (duodenum, jejunum, and ileum) 6- Large intestine (caecum, colon, and rectum) Q.2) How is food mechanically broken down during digestion? Answer:   The digestion of food is completed by both mechanical digestion and chemical digestion. In mechanical digestion, food is physically broken down into smaller pieces by the acts of chewing (mouth) and churning (stomach). 1) Chewing:   The break down of food by the grinding action of teeth is called chewing. After chewing, the food enters the stomach from the oesophagus. 2) Churning:   The walls of the stomach are thick and ...

Mardan board (KPK) Physics class 9 Chapter 2 (Kinematics) notes are written in easy words. Important questions are also given in Kinematics Chapter 2 notes. Physics class 9 Chapter 2 (Kinematics) Conceptual Questions Is it possible that displacement is zero but not the distance ? Under what condition displacement is equal to the distance?Yes, it is possible that the displacement is zero but distance is not zero. For example, a student leaves school from point A. He moves 3m north and reaches point B, 5m in the west to reach point C. Then 3m in the south to reach point D and finally 3m to east and comes the same initial point A. Here the path traveled is 3 + 5 + 3 + 5 = 16m. Here path traveled is distance which is 16 m. But the student is in the same point where he was initially hence his displacement is zero as shown in figure below. The distance and displacement will be equal when a motion of a body from one point to another point is in a straight line. For example, Suppose a body onl...

KPK (Mardan) Physics Class 9 Chapter 3 Dynamics Short Questions Answers and long question, Conceptual Questions, Comprehensive Questions, and Numerical Questions. KPK (Mardan Board) Physics Class 9 Chapter 3 Dynamics Conceptual Questions Q.1) Why does dust fly off, when a hanging carpet is beaten with a stick? Answer: When a hanging carpet is beaten with a stick, it moves forward along with the dust particles but when the carpet moves back due to inertia, the dust continues its motion in the forward direction, therefore, dust flies off from the carpet. Q.2) If your hands are wet and no towel is handy, you can remove some of the excess water by shaking them. why does this work? Answer: When we shake the hands, the shaking brings the hands in motion but the water drops try to remain in rest due to the inertia of rest and are removed from the hands, in this way, we can remove some of the excess water. Q.3) Why a balloon filled with air move forward, when its air is released? Answer: Expl...

questions, answers, Conceptual Questions, Comprehensive Questions, and, Numerical Questions Mardan board (KPK ) Physics Class 9 Chapter 6 Work and Energy. Conceptual Questions Physics Class 9 Chapter 6 Work and Energy Q.1) Can a centripetal force ever do work on an object? Explain. Answer: No, centripetal force does not do work because the force acting on the object and instantaneous displacement of the object are always perpendicular to each other as shown in the figure. So;                      W = FS cosϴ = FS cos90° = FS(0) = 0 J The centripetal force allows the object to follow the circular trajectory. The centripetal force is directed towards the center while the tangential velocity of the object is perpendicular to the direction of action of force at every point. Hence no work can be done by it. Q.2) What happens to the kinetic energy of a bullet when it penetrates into a sandbag? Answer: When a bullet of mass 'm' is moving with velocity 'v' it possesses kinetic ...

Thermal Properties of Matter Physics Class 9th Notes Chapter 8. Heat is the form of energy transferred between two (or more) systems or a system and its surroundings by virtue of temperature difference. Physics Class 9th Notes Chapter 8 Thermal Properties of Matter Q.1) Ordinary electric fan increases the kinetic energy of the air molecules caused by the fan blades pushing them means the air temperature increases slightly rather than cool the air? why use it? Answer: Ordinary fans work on the principle of convection. The moving air increases the rate of evaporation or perspiration from our bodies, so we get a cooling sensation. The flowing air takes away the heat from the body and is replaced with the colder air. Q.2) Why are small gaps left behind the girders mounted in walls? Answer:     Usually, small gaps are left behind the girders mounted in walls to give room for expansion. One end of the iron is fixed while the other end is allowed to expand into the left out gaps in summer. Q...

Chapter 7 Electrochemistry Chemistry 9 class Notes short, long question numerical These 9th class chemistry notes prepared according to the syllabus of all KPK Mardan board. Other boards other than Punjab do not follow class 9 chemistry notes. Short Questions Chapter 7 Electrochemistry Chemistry 9 Q.1) Indicate which element is reduced in the following reaction: a) Ca(s) + Br2(g) → CaBr2(s) b) 8H+ + MnO-4 + 5e- → Mn2+ + 4H2O Answer: a) Ca(s) + Br2(g) → CaBr2(s) There is a decrease in oxidation number of Br2, from 0 to -1. So Br2 is reduced. b) 8H+ + MnO-4 + 5e- → Mn2+ + 4H2O There is a decrease in oxidation number of Mn, from +7 to +2. So Mn in reduced.  Q.2) What is the oxidation number of silver on each side of the following equation? heat 4Ag(s) + O2(g) → 2Ag2O(s) Answer: For the left side of equation: The oxidation number of all elements in the free state is zero. Therefore on the left side of the equation, oxidation state of silver is zero. For the right side of equation: 2 + = 0...